A NOVEL NUMERICAL TECHNIQUE FOR DIELECTRIC MEASUREMENT OF GENERALLY LOSSY DIELECTRICS

A method for determining the dielectric properties of infinite half-space of generally lossy dielectric materials is described. This method utilizes the measurement of the admittance of a rectangular waveguide radiating into such dielectrics. It is shown that the real part of the admittance is relatively insensitive to the variations of the imaginary part of the dielectric constant. Subsequently, a numerical procedure is initiated which provides a simple and fast-converging approach for calculation of the dielectric properties of the material. This numerical procedure renders itself to implementation by personal computers-a major advantage over the existing computational schemes. The theoretical formulation for the expression of the admittance of an open-ended waveguide and the numerical procedure to calculate the dielectric properties are discussed in detail. Results of several measurements of free-space and lossy dielectric samples (rubber with carbon black) to verify the theory and the numerical scheme are given as well. The results of this technique were also compared with other measurement schemes, and very good agreement was obtained. Comments on the accuracy of the results are also provided.